The present disclosure relates to semiconductor memory devices, and more particularly to nonvolatile memory such as electrically erasable programmable read only memory (EEPROM).
In EEPROM, the memory contents in memory cells can be erased and rewritten using electric signals. In specific write operation, hot carrier injection (HCI) is used in some cases. In such cases, the output of a first regulator is coupled to the gate of a memory cell, and also the output of a second regulator is coupled to the gate of a voltage applying transistor, so that the gate voltage of the memory cell is regulated while a voltage is applied from the drain terminal of the voltage applying transistor to the drain terminal of the memory cell. A technique like this is described in Japanese Patent Publication No. 2008-217914 (FIG. 9), for example.